• Proceedings of the KWS Conference
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• 2009.11a
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• pp.99-99
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• 2009

마그네슘은 지구상에서 존재하는 금속 중 가장 가벼운 실용화 금속이다. 따라서 최근 산업 전반적으로 대두되는 경량화에 대응하는 데 중요한 소재로 각광받고 있으며 그 활용이 활발하게 추진되고 있다. 본 연구에서는 이러한 동향에 대응하는 일환으로 POSCO에서 생산되고 있는 압연 마그네슘판재를 적용하였다. 적용 대상은 철도 분야의 경량화를 위한 전장품을 선정하고, 실물 크기로 제작하였다. 제작은 두께 3.5 mm 의 판재를 사용하였으며 용접은 Friction Stir Welding 및 GTAW 를 사용하였다. 그림1에 제작이 완료된 형상을 나타낸다. 그리고 제작중의 용접과정에 대하여 3차원 열탄소성 해석을 수행하여 변형 과정에 대한 검토를 수행하였다. 그림2에 해석과정의 한 예를 나타낸다.

• Proceedings of the KSR Conference
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• 2005.05a
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• pp.385-390
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• 2005

A specimen with residual stress due to welding was analyzed by three-dimensional cohesive zone model. The residual stress distribution was calculated by simulating welding process, and cohesive elements were located along crack propagation planes. Crack growth is possible since two planes of the cohesive element are separated beyond a maximum load carrying capacity. Stress fields around a crack tip are compared for specimens with and without residual stresses. Load-displacement curves and crack growth behaviors are also examined.

• Journal of Korean Association for Spatial Structures
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• v.11 no.4
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• pp.37-47
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• 2011

This article aims to analytically research for influence of residual stresses on bending moment responses against welded steel pipes subjected to quasi -static or dynamic loadings. The residual stresses of the welded steel pipe are computed by three-dimensional welding simulation. The bending moment responses of the welded and seamless steel pipes are determined by using three-dimensional dynamic elastoplastic FE analysis as a function of loading rate. It is seen from analytical results that the welded steel pipe shows lower moment response comparing to the seamless steel pipe, and moment difference between seamless and welded steel pipes tends to decrease as loading rate increases.

• Proceedings of the KWS Conference
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• 2010.05a
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• pp.55-55
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• 2010

마그네슘 판재는 경량화 소재로 주목받는 소재이다. 본 연구는 압연 마그네슘 판재의 용접시 발생하는 온도이력 및 응력에 대한 해석을 수행하였다. 해석은 2차원 해석을 수행하였으며 해석수행에 있어서 열물성값은 기존의 데이터를 이용하였으며 응력해석은 온도별 고온 인장시험을 수행한 결과를 이용하여 해석을 수행하였다. 본 연구에서 수행한 대상은 마그네슘 압연판재인 AZ31B 이며 두께 3.5 mm 판재를 GTAW용접을 수행한 경우에 대하여 검토하였으며, 해석결과 중 온도분포의 한 예를 그림 1에 나타낸다.

• Proceedings of the KWS Conference
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• 2005.06a
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• pp.103-105
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• 2005

Laser welding technology for automobile body is studied. laser system, robot and seam tracking system are used for 3D laser welding system The laser system is used 4kW Nd:YAG laser(HL4006D) of Trumpf and the robot system is used IRB6400R of ABB. The seam tracking system is SMRT-20LS of ServoRobot. The welding joints of steel plate are butt and lap joint. The 3-D welding for non-linear tailored blank is performed after experiments of bead on plate. Finally, the welding process for non-linear tailored blank is developed.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.9
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• pp.1311-1316
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• 2010

In this study, straight slot welding was carried out using a 316L stainless steel test block, and numerical simulation of the slot weld process was performed using finite element analysis. Data on the residual stress were obtained at equally spaced points on the top surface of the test block along directions parallel and perpendicular to the welding direction. After electrolytic polishing of the top surface of the block, the residual stress was measured by the X-ray diffraction method. The calculated weld residual stresses were compared with the measured data, and they were in good agreement with the data. The weld residual stress distribution inside the plate was determined from the results of finite element analysis, and the characteristics of the distribution were discussed in detail in this paper.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.4
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• pp.401-408
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• 2009

This study is performed to check the three dimensional characteristics of residual stress in the dissimilar metal weld. Although two dimensional analysis has been widely used for the assessment of weld residual stress, it has limitations to understand the stress distribution of the third direction. 3-D analysis was done to understand residual stress distribution of the welded plate. A simple butt-welded plate was considered to show the stress variation on all direction. A mock-up plate weldment was fabricated with SA-508 and F316L, which are widely used in nuclear power plants. The analysis results were validated with the measured values in the mock-up.

• Journal of Welding and Joining
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• v.27 no.3
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• pp.32-37
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• 2009

• Journal of Welding and Joining
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• v.29 no.3
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• pp.39-44
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• 2011

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1499-1504
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• 2007

Spot-welding is widely used to construct passenger car bodies in automotive industry. Occasionally severe spot-weld distortions in sub-assembly make further spot-weld difficult. In this paper, distortions for various spot-weld conditions are measured using coordinate measuring machine. Then, based on finite element solution for unit translation or unit rotation of nugget edge, equivalent loads for spot-weld distortions are determined. They can be used to predict the spot-weld distortion using finite element method.